hese days, it isnít just that Republicans are from Mars and Democrats are from Venus. Increasingly, politicians on either side are cherry-picking evidence to support their version of reality.What is cherry-picking? Itís the tactic of harnessing an incomplete and unrepresentative set of evidence to misleadingly make a broader argument. These days, politicians use the tactic to appeal directly to their base while dropping the pretense that they are reaching out to anyone on the other side.Cherry-picking doesnít necessarily have to be problematic: In a debate, no one expects politicians to provide both their own perspective and that of their opponents. Advocacy groups understandably put the most sympathetic personalities out front when making arguments, rather than relying on dry, faceless numbers.Still, several historical safeguards that prevented cherry-picking from overtaking politics have weakened in recent years, including the collapse of the political center, the weakening of media neutrality, and the politicization of previously independent congressional committees.A harder-edged use of cherry-picking is the recent debate over whether to release a memo authored by the staff of House Intelligence Committee Chairman Devin Nunes, R-Calif.Nunes, President Donald Trump, conservative commentators, and many Republican officials wanted the memo released. The GOP memo claimed that federal officials selectively withheld information when they obtained a warrant to monitor Carter Page, a former Trump campaign associate suspected of working as a Russian agent.Critics ó including Democrats, current and former national security officials, and many commentators from both parties ó argued that the authors chose to include only the pieces of evidence that fit their narrative, leaving out any intelligence that told a different story.The Nunes memo offers an unusual example of alleged political cherry-picking, since it involves classified information. Democrats are now seeking to release their own memo. The Intelligence Committee has approved its release, but as with the Nunes memo, the final decision is up to President Donald Trump. If and when a Democratic response comes out, Republicans will likely accuse it of using cherry-picked evidence as well.The memo is emblematic of an era in which politicians have relied to an increasing degree on cherry-picking as a rhetorical weapon."Polarization makes each of the two opposing sides in Congress uninterested in finding middle or common ground, or objective truth about a situation," agreed Charles Tiefer, a law professor at the University of Baltimore and author of The Polarized Congress: The Post-Traditional Struggles of its Current Procedure. "Instead, the opposing sides just pick out what they like or what supports their separate stance."Can be benignCherry-picking ó the origin of the phrase is unclear but likely is connected to the fact that actual cherries are picked by hand ó may have entered a new era of importance, but it also has been around a long time."There has always been a lot of lying, fabricating, and general bull---- in politics," said Bert Rockman, an emeritus political science professor at Purdue University and co-editor of The Oxford Handbook of Political Institutions and Presidential Leadership: The Vortex of Power. "There was Joe McCarthy, after all, and Richard Nixon. Going back farther in time, we had the party-run press. So while I donít think what we are witnessing is anything dramatically different in kind, it seems to be greater in degree."Itís worth noting the existence of more justifiable uses of cherry-picking. In the justice system, a defense attorney argues the best, and usually incomplete, case for their client, while the prosecutor (with some legal limitations) emphasizes the evidence that makes the defendant seem most guilty.What makes the court system different from the political system, however, is that a judge with relatively unfettered powers keeps the process and the evidence as fair as possible to all parties.The framers "anticipated the possibility of corruption," said Kermit Roosevelt, a law professor at the University of Pennsylvania. "What they didnít anticipate was the party system, which turned democracy into an adversarial system in which people put party above country and advocate for their party in the way a defense lawyer does for a client. Criminal justice works okay as an adversarial system. Democracy doesnít."High-profile examplesIn our decade-plus of fact-checking, PolitiFact has seen cherry-picking repeatedly, and from representatives of both parties. Search our website and youíll find that the term comes up hundreds of times in our fact-checks. But cherry-picking has played an especially important role in several recent, high-profile episodes.In addition to the fight over the Nunes memo, cherry-picking can be seen in the story of former FBI agent Peter Strzok, who was removed from Robert Muellerís special counsel inquiry for the content of texts between him and fellow FBI official Lisa Page, with whom he was reportedly having an affair.Critics of the Mueller investigation, using the cache of recovered texts between the two, seized on examples in which Strzok appeared to be biased against Trump and used them to shape a months-long narrative of bias by the FBI official. But later, CNN reported that other Strzok texts ó ones not initially highlighted by the critics ó undercut that narrative. And a subsequent review of the cache by Wall Street Journal reporter Del Quentin Wilber found that "texts critical of Mr. Trump represent a fraction of the roughly 7,000 messages. .?.?. Rather, a broader look shows an unvarnished and complex picture of the lives of an FBI agent and lawyer who found themselves at the center of highly charged probes."Cherry-picking also recurred regularly in the debate over the recently passed tax bill, which was supported by Trump and most Republicans and opposed by all congressional Democrats. To hear Democrats talk about the bill, no middle-class taxpayers stood to gain from the tax bill. To hear Republicans talk about it, only middle-class taxpayers would gain from the tax bill. (Generally speaking, the law provides income gains for most taxpayers up and down the income scale in the earlier years, but the benefits concentrate among wealthier Americans in the later years.)Meanwhile, Trump has made many claims that use cherry-picked data. He has often touted achievements on his watch that simply continued longstanding trends that began under President Barack Obama, such as a decline in African-American unemployment, an increase in wages, and an absence of plane crashes. He has also cherry-picked data to support his popularity in polls, and he released a campaign ad that focused on an undocumented immigrant charged with killing two police officers, when data shows that undocumented immigrants are not unusually prone to criminal behavior.Sooner or laterNo one is immune from cherry-picking. Democrats have used the technique regularly, as have other Trump critics.In 2016, the Democratic nominee against Sen. Richard Burr, R-N.C., said in an ad that Burr "voted no on the Violence Against Women Act." We found that Burr did vote against the 2012 version of the lawís reauthorization, which was considered a significant vote at the time. However, the ad ignored three other times over 13 years that Burr did vote for a reauthorization. We rated the statement Half True.The same year, Hillary Clinton, Trumpís opponent, earned a Pants on Fire for saying FBI director James "Comey said my answers were truthful, and what Iíve said is consistent with what I have told the American people." Comey had specifically declined to comment on whether Clintonís public remarks had been accurate generally.Trump himself has occasionally been the victim of cherry-picked accusations. The Club for Growth, a group that opposed Trump during the 2016 primaries, said Trump was promising "to take care of everybody" through government-run health care and that "the governmentís going to pay for it." But it was clear from Trumpís website and some of his public comments that he wanted a market-based approach to health care. We rated it False.More common?So is there more cherry-picking today in political rhetoric than in the past? Thatís hard to say ó we couldnít find anyone who measures it. But several political scientists and historians said that even if itís not more common, the use of the tactic may have turned a corner.Kyle Saunders, a Colorado State University political scientist, said whatís different is how often political elites are using the tactic and the relative unanimity of that messaging."Steven Smith, a political scientist at Washington University in St. Louis, traces the pattern to the rise of Newt Gingrich, the Georgia Republican who became House speaker after a Republican wave in the midterm elections of 1994."The Gingrich strategy included an important theme: simplify and repeat," Smith said. "It is message politics over policymaking, salesmanship over education. Simplification and repetition generate messages that lack nuance, which inevitably forces the messages away from reality" -ó which is, more often than not, nuanced.Republicans, Smith said, "have become adherents of the Gingrich school by virtue of associating their electoral successes since 1994 to it. Democrats have only poorly followed suit."PolarizationSeveral other trends have reinforced the Gingrich approach, experts said.One is the growing polarization of the parties, especially in Congress. "Itís clear that the harsh partisanship in Congress and the media has made the whole situation even worse than it was," said former U.S. Rep. Martin Frost, D-Texas. "Congress has tried until recently to be bipartisan on serious foreign policy matters," but the effort to release the Nunes memo "totally undercuts that."This tendency has been fueled by safe House seats ó seats where one party has a near-certain lock on victory ó which have multiplied due to a combination of natural geographic sorting and sophisticated gerrymandering techniques. Increasingly, a lawmakerís most important concern is surviving a primary, something that pulls them to the right (for Republicans) and left (for Democrats) in order to satisfy the most active primary voters. In many cases, the November general election is "just a constitutional formality," said former Rep. Tom Davis, R-Va. "Thereís no reward for reaching out to middle."Actual debate is rarely valued any more in Congress, said Richard E. Cohen, a longtime congressional correspondent and lead author of the Almanac of American Politics. "Arguably, the context has changed, because the paucity of serious debate on Capitol Hill has meant that more attention is paid to clever talking points than to serious substance," he said.Another culprit: The contemporary media, which, shaped by the click-driven influences of social media, has offered advantages to politicians who offer clear, outspoken positions rather than nuanced explanations. "Cherry-picking news and interpretations of events can grab and hold an audience, and this pattern is not lost on candidates and elected officials," said Smith, the Washington University political scientist.Even if coverage with a more complete, nuanced narrative eventually materializes, it is often drowned out in the clutter, Smith added. Politicians who cherry-pick facts "count on Ďeven-handedí reporting and know that the audiences they care about will not see and hear the follow-up analyses offered days later or in a different location," he said.Institutional decayAs neutral media arbiters fade in influence, so have neutral political institutions, said Tiefer, who between 1984 and 1995 worked with the House Intelligence Committee, the panel now headed by Nunes. Back when he worked for the committee, lawmakers "always sought consensus and bipartisan oversight of the intelligence agencies," he said. "There was a bipartisan consensus about the legitimate ways to present a position on subjects, including intelligence subjects, that is quite forgotten today."The general public doesnít escape blame, either. Many Americans live in "bubbles" where a desire to confirm oneís existing views makes people "ripe for cherry-picked arguments," said Davis, the former Republican lawmaker.This environment has helped create "apocalyptic thinking" that partisans think frees them from any need to restrain their tactics out of respect to longstanding norms and taboos, said David Greenberg, a historian at Rutgers University and author of Republic of Spin: An Inside History of the American Presidency."Liberals see Trump as a would-be authoritarian, even as a fascist," he said. "Conservatives spoke of (defeating Hillary Clinton as) the Flight-93 election ó a last chance to save democracy. This brings out a willingness to justify hardball political tactics, including the use of propaganda, of which cherry-picking is one form."Blame the human mind, Smith said. "The human mind is pliable," he said. "Biases run deep when they are strongly reinforced by political elites and the media. Political elites exploit this."Contact Louis Jacobson at [email protected] Follow @loujacobson.